System and method for heating a gasifier

ABSTRACT

A system includes a gasifier injector configured to inject a heat control fuel and a mixed air into a gasifier for combustion during a heat control mode. The heat control fuel is the same or different from the gasification fuel, and the system is configured to create the mixed air from independent supplies of oxygen and nitrogen.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates generally to gasifiers. Moreparticularly, the disclosed subject matter relates to a system andmethod for heating a gasifier.

Gasification systems generally include a process injector used to supplya gasification fuel, such as an organic feedstock, into a gasifier alongwith oxygen and steam to generate a syngas. As a preliminary step, amixture of a preheat fuel and air is combusted to preheat the gasifierto an elevated temperature before initiating gasification of thefeedstock in the gasifier. Unfortunately, the elevated temperatureachievable during preheat may be substantially limited by the use of airand low pressures (e.g., atmospheric pressure). As a result of thistemperature limit, if the process injector cannot be installed quicklyenough after preheat, then the gasifier temperature may drop below atemperature threshold suitable to start gasification of the feedstock.In the event of such excessive cooling, the preheat process would needto be repeated to raise the gasifier temperature to the elevatedtemperature. As a result of this delay, valuable time may be lost forgasifying the feedstock, which in turn may result in lost production ofchemicals, lost generation of electricity, and so forth. The use of airand low pressures (e.g., atmospheric pressure) also may substantiallylimit the rate of temperature increase and the overall time required tocomplete the final stages of preheat. Again, this delay can result insignificant losses in gasification production.

BRIEF DESCRIPTION OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimedinvention are summarized below. These embodiments are not intended tolimit the scope of the claimed invention, but rather these embodimentsare intended only to provide a brief summary of possible forms of theinvention. Indeed, the invention may encompass a variety of forms thatmay be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a gasifier injector configuredto inject a heat control fuel and a mixed air into a gasifier forcombustion during a heat control mode. The heat control fuel is the sameor different from the gasification fuel, and the system is configured tocreate the mixed air from independent supplies of oxygen and nitrogen.

In a second embodiment, a system includes a controller configured tocontrol a heat control mode of a gasifier injector coupled to agasifier. The heat control mode of the gasifier injector is configuredto control injection of a heat control fuel and a mixed air into thegasifier for combustion, and the heat control fuel is the same ordifferent from a gasification fuel used during a gasification mode inthe gasifier. The controller is configured to control generation of themixed air from independent supplies of oxygen and nitrogen, and the heatcontrol mode is configured to control heating of the gasifier to atemperature at or above a temperature threshold while the gasifier isnot operating in the gasification mode

In a third embodiment, a method includes controlling a heat control modeof a gasifier injector coupled to a gasifier. Controlling the heatcontrol mode includes controlling generation of a mixed air fromindependent supplies of oxygen and nitrogen and controlling injection ofa heat control fuel and the mixed air into the gasifier for combustion.The heat control fuel is the same or different from a gasification fuelused during a gasification mode in the gasifier. Controlling the heatcontrol mode also includes controlling heating of the gasifier to atemperature at or above a temperature threshold while the gasifier isnot operating in the gasification mode.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic representation of an embodiment of a gasificationsystem that may utilize oxygen enriched air for heat control of agasifier;

FIG. 2 is a schematic representation of an embodiment of certaincomponents of the gasification system of FIG. 1 for use with a preheatinjector;

FIG. 3 is a schematic representation of an embodiment of certaincomponents of the gasification system of FIG. 1 for use with acombination injector;

FIG. 4 is a flow chart of an embodiment of a method for heating agasifier with oxygen enriched/manufactured air using a preheat injector;

FIG. 5 is a flow chart of an embodiment of a method for heating agasifier with oxygen enriched/manufactured air and operating thegasifier using a combination injector;

FIG. 6 is a flow chart of an embodiment of a method for operatingcertain components of a gasification system in an oxygen enriched airheat mode;

FIG. 7 is a graphical representation of an embodiment of gasifierheating when operating a gasifier in an air/fuel heat mode and in anoxygen enriched air/fuel heat mode;

FIG. 8 is an axial perspective view of an embodiment of a fuel injectoroperating in a gasification mode and operating in an oxygenenriched/mixed air heat mode;

FIG. 9 is an axial perspective view of an embodiment of a fuel injectoroperating in a gasification mode and operating in an oxygen enriched airheat mode;

FIG. 10 is a schematic representation of an embodiment of a gasificationsystem that may manufacture air for heat control of a gasifier;

FIG. 11 is a schematic representation of an embodiment of certaincomponents of the gasification system of FIG. 10 for use with a preheatinjector;

FIG. 12 is a schematic representation of an embodiment of certaincomponents of the gasification system of FIG. 10 for use with acombination injector;

FIG. 13 is a flow chart of an embodiment of a method for operatingcertain components of a gasification system in a heat control mode usingmanufactured air;

FIG. 14 is a schematic representation of an embodiment of certaincomponents of a gasification system with a preheat injector, includingflow lines for manufacturing air and/or enriching air with oxygen; and

FIG. 15 is a schematic representation of an embodiment of certaincomponents of a gasification system with a combination injector,including flow lines for manufacturing air and/or enriching air withoxygen.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

When introducing elements of various embodiments of the presentinvention, the articles “a,” “an,” “the,” and “said” are intended tomean that there are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.

The present disclosure is directed to a system and method for heating agasifier using manufactured air. A gasification system may manufactureair from independent supplies of oxygen and nitrogen and inject themixed air and a heat control fuel into the gasifier for combustion toheat the gasifier when the system is not operating in a gasificationmode. An injector may inject the mixed air into the gasifier when thesystem operates in a mixed air/fuel heat mode to heat a refractory linerof the gasifier. A controller configured to control the mixture of theoxygen and nitrogen for manufacturing the mixed air may increase theconcentration of oxygen flowing into the gasifier through the injector.This may provide increased heating to the gasifier because of therelatively lower concentration of nitrogen in the mixed air. In thisway, the controller transitions the gasification system from the mixedair/fuel heat mode to an oxygen enriched mixed air heat mode in order toheat the refractory liner of the gasifier above a temperature threshold.

Turning now to the drawings, FIG. 1 is a schematic representation of anembodiment of a gasification system 10 that may utilize oxygen enrichedair for heat control of a gasifier. The gasification system 10 includesa gasifier 12, injector 14, gas treatment unit 16, vent system 18, asupply unit 20, and a controller 22. The gasifier 12 is configured togasify a gasification fuel 24 supplied to the gasifier 12 through theinjector 14. The supply unit 20 may be one or more units for preparing,storing, and/or conveying various supplies that may be injected into thegasifier 12 through the injector 14.

The gasification fuel 24 may include a variety of carbonaceous fuels,such as coal, or hydrocarbons, in a solid or liquid form, or gaseousfeeds (e.g., natural gas or fuel gas). The supply unit 20 may include agasification fuel supply 26, which may include a unit for preparing thegasification fuel 24 for gasification, e.g., by milling, shredding, andpulverizing a solid form of the gasification fuel 24. Once prepared forgasification, the gasification fuel 24 may be transmitted from thegasification fuel supply 26 to the gasifier 12 as needed. The gasifier12 may convert the gasification fuel 24 into a syngas, e.g., acombination of carbon monoxide (CO) and hydrogen (H₂). This resultantgas may be termed untreated syngas, because it includes, for example,H₂S. The gasifier 12 may also generate byproduct material, such as slag,which may be a wet ash material. The gas treatment unit 16 may beutilized to clean the untreated syngas. The gas treatment unit 16 mayscrub the untreated syngas to remove the HCl, HF, COS, HCN, and H₂S fromthe untreated syngas. Furthermore, the gas treatment unit 16 mayseparate salts from the untreated syngas through water treatmenttechniques to generate usable salts from the untreated syngas.Subsequently, the gas from the gas treatment unit 16 may include treatedsyngas (e.g., the sulfur has been removed from the syngas), with traceamounts of other chemicals, e.g., NH₃ (ammonia) and CH₄ (methane). Thistreated syngas may then be transmitted to a downstream process 28, powergeneration system 30, or chemical production system 32. For example,syngas from the gas treatment unit 16 may be transmitted to a combustorchamber of a gas turbine engine in order to fuel a power generationprocess. The gas treatment unit 16 also may provide a back pressurecontrol of the gasification system 10 during gasification, the backpressure control being provided in sections of the gas treatment unitused for cleaning and/or cooling the syngas. When the system 10 operatesin a heat control mode using a combination injector, however, the ventsystem 18 may include a back pressure control that may be used to adjusta pressure in the gasifier 12.

The gasifier 12 may include a gasification chamber 34, wheregasification takes place, a refractory liner 36 disposed about thegasification chamber 34, and an enclosure 38 disposed about therefractory liner. The refractory liner 36 may be made of a refractorymaterial (e.g., ceramics) and designed to act as a thermal protectivelayer within the gasifier 12. In addition to protecting the enclosure 38from high temperature operation, the refractory layer 36 may controlheat loss and serve as a source of heat for a combustion process used tostart the gasifier 12. Indeed, the refractory liner 36 may be heated toa temperature at or above a temperature threshold before the gasifier 12becomes operable in a gasification mode.

In addition to the gasification fuel supply 26, the supply unit 20 mayinclude an oxygen enriched air (EA) supply 40, heat control fuel (HCF)supply 42, oxidant supply 44, moderator supply 46, and a purge supply48. In the illustrated embodiment, the oxygen enriched air supply 40supplies oxygen enriched air, which includes air 50 enriched withadditional oxygen 52, to the first injector 14. Likewise, the HCF supply42 supplies HCF 54, which may be the same or different from thegasification fuel 24, to the first injector. For example, the HCF 54 maybe a clean fuel, such as natural gas, whereas the gasification fuel 24may be a slurry of coal mixed with water. The first injector 14 injectsthe incoming HCF 54 and oxygen enriched air to the gasifier 12 forcombustion during a heat control mode (e.g., preheat or heatmaintenance) of the gasification system 10. That is, when the gasifier12 is not operating in a gasification mode, oxygen enriched air and theHCF 54 may be supplied to the gasifier 12 in order to heat therefractory liner 36 of the gasifier 12 to a temperature at or above adesired gasifier temperature threshold. This may apply to bothpreheating operations and heat maintenance operations, which arediscussed in detail below.

The oxidant supply 44 may provide a desired amount of gasificationoxidant (GO) 56, such as oxygen, to the injector 14. A mixture ofnitrogen gas 58 and steam 60 may be provided to the injector 14 as wellvia the moderator supply 46, and nitrogen gas 62 and/or steam also maybe supplied to the injector 14 via the purge supply 48. In otherembodiments, the moderator supply 46 may provide recycled CO₂ or syngasto the injector 14 for use as a moderator during the gasification mode.The moderator (e.g., nitrogen 58 and/or steam 60, CO₂, or syngas),gasification fuel 24, and gasification oxidant 56 are supplies usedduring gasification, which may be sequenced into the gasifier 12 throughinjector 14, flowing continuously through injector 14 while the system10 operates in a gasification mode. The purge supply 48 may be used topurge certain passages within the injector 14 during specific operationsof the gasifier 12, e.g., purging the injector 14 of HCF 54 whenchanging from a heat control mode to a gasification mode. An airseparation unit may operate to separate air supplied by an aircompressor into component gases by, for example, distillation techniquesfor providing certain supplies (e.g., additional oxygen 52, gasificationoxidant 56, and/or nitrogen 58 and 62). The air separation unit also mayprovide oil-free air 50, or oil-free air 50 may be provided by adedicated air compressor.

The controller 22 is configured to control a heat mode of the injector14 coupled to the gasifier 12 based on sensor feedback. That is, thecontroller 22 may control an amount of the additional oxygen 52 in theoxygen enriched air based on sensor feedback. It should be noted thatwhenever the controller 22 adjusts (e.g., increases) the amount of theadditional oxygen 52 in the oxygen enriched air, the controller 22 alsomay adjust (e.g., decrease) the amount of air flowing to the injector 14in order for the feeds to produce a desired flame temperature (e.g.,maintain or increase the flame temperature) in gasifier 12. Thegasification system 10 may include at least one sensor to obtain sensorfeedback indicative of a temperature, a pressure, a fuel parameter ofthe HCF 54, a purity of the additional oxygen 52, a property of the air50, a property of the oxygen enriched air, a parameter of the gasifier12, or a combination thereof For example, the controller 22 may receivesensor feedback indicative of a temperature from a sensor 64 located inthe gasifier 12. Although shown coupled to the refractory liner 36 ofthe gasifier 12, this sensor 64 may be placed on other components aboutthe gasifier 12 and calibrated to provide an approximate temperature ofthe refractory liner 36 or other gasifier components. Additional sensors66, 68, 70, 72, 74, 76, and 78 may measure parameters from othercomponents of the system 10 including the injector 14, gas treatmentunit 16, vent system 18, supply unit 20, downstream process 28, powergeneration system 30, and chemical production system 32, respectively.The controller 22 may control the operations of gasifier 12, injector14, gas treatment unit 16, vent system 18, supply unit 20, downstreamprocess 28, power generation system 30, and chemical production system32 based on the feedback received from the sensors 64, 66, 68, 70, 72,74, 76, and 78. The controller 22 may also operate supply valves 80 inorder to permit a desired flow of heating and gasification supplies fromthe supply unit 20 to the injector 14 based on the sensor feedback. Forexample, during the transition from heat control mode to gasificationmode, as further discussed below, the sensor 64 may measure atemperature of the refractory liner 36 that is below the desiredthreshold temperature of the gasifier 12. In response, the controller 22may control the valves 80 in order to prevent flow of the gasificationfuel 24 and gasification oxidant 56 to the injector 14 unless thegasifier 12 is at or above the threshold temperature for operating inthe gasification mode.

It should be noted that although the illustrated embodiment includes asingle supply unit 20 and series of valves 80 for controlling the flowof supplies to the injector 14, other arrangements may be possible. Forexample, the heat control supplies (i.e., the oxygen enriched air supply40 and HCF supply 42) may be in a different location than thegasification supplies (i.e., the GF supply 26, oxidant supply 44,moderator supply 46, and purge supply 48). Also, the nitrogen 58 usedfor the moderator supply 46 and the nitrogen 62 used for the purgesupply 48 may come from a common source of nitrogen. In addition, theheat control supplies may include additional and separate purges.Moreover, one or more of valves 80 used to control the flow of thesesupplies to the injector 14 may be positioned upstream of or within thesupply unit 20, allowing, for example, the controller 22 to vary theoxygen concentration of the enriched air supply 40 before the enrichedair reaches or flows from the supply unit 20.

FIG. 2 is a schematic representation of an embodiment of certaincomponents of the gasification system 10 of FIG. 1 that may be used whenthe injector 14 is designed for heating of the gasifier 12. In certainembodiments, the illustrated injector 14 may be a preheat injector usedto preheat the refractory liner 36 of the gasifier 12 to a desiredtemperature prior to operating the gasifier 12 in gasification mode. Inother embodiments, the injector 14 may be a heat maintenance injectorused to maintain heat in the refractory liner 36 after operating thegasifier 12 in the gasification mode, but before restarting the gasifier12 in the gasification mode. The injector 14, when used for heatingonly, may be removed and replaced with a second injector to inject thegasification fuel, oxidant, and moderator into the gasifier 12 forgasification during the gasification mode. Whether used for preheatingthe gasifier 12 or maintaining heat in the gasifier 12, the injector 14,which may be the same or a different injector for preheating andmaintaining heat, is configured to inject heat control supplies 92 intothe gasifier 12. Once injected into the gasifier 12, the HCF 54 and air50 are combined and ignited, establishing combustion within the gasifier12 to heat the refractory liner 36 to the desired temperature. It shouldbe noted that the injector 14 includes multiple passages through whichthe heat control supplies 92 (i.e., the HCF 54, air 50, and oxygenenriched air 40) are routed to the injector 14. The different routesthrough the injector may facilitate the combination of the heat controlsupplies 92 as they enter the gasifier 12.

Based on the desired function of the injector 14, the controller 22operates the valves 80 to control the flow of the corresponding heatcontrol supplies 92 to the injector 14 and from the injector 14 into thegasifier 12. The controller 22 may operate these valves 80 and othercomponents of the gasification system 10 according to a heat controlmode 94. In the heat control mode 94, the injector 14 is configured toinject the HCF 54 and either the air 50 or the oxygen enriched air 40into the gasifier 12 for combustion during the heat control mode 94. Theheat control mode 94 may include a preheat mode 96 configured to operatethe valves 80, first injector 14, and gasifier 12 in order to preheatthe gasifier 12 prior to operating the gasifier 12 in a gasificationmode. Additionally, the heat control mode 96 may include a heatmaintenance mode 98 for operating the valves 80, first injector 14, andgasifier 12 in order to maintain heat within the refractory liner 36 ofthe gasifier 12. Further, the heat control mode 94 may include a heatcontrol transition 100 from an air/fuel heat mode 102 to an oxygenenriched air/fuel heat mode 104, allowing the system 10 to increase anddecrease a ratio of the additional oxygen 52 to the air 50 and a flowrate of the air 50. For example, at the beginning of the preheat mode 96or the heat maintenance mode 98, the controller 22 may position thevalves 80 such that an HCF valve 106 and a first air valve 108 areopened and oxygen valve 112 is maintained closed. This corresponds tothe controller 22 operating the system 10 in the air/fuel heat mode 104(i.e., no oxygen enrichment of the air). As the system 10 continues tooperate in the heat control mode 94 and the refractory liner 36increases in temperature, the heat control transition 100 may controlthe valves 80 to open the oxygen valve 112 and partially close air valve108. Consequently, the oxygen 52 is added to a reduced amount of air 50,and the oxygen enriched air 40 is supplied to the injector 14 forheating the refractory liner 36 of the gasifier 12. The composition andflow rate of the oxygen enriched air 40, which contains a lowerpercentage of nitrogen and a higher percentage of oxygen than the air50, may thus be controlled to allow the temperature of the refractoryliner 36 to increase above a temperature that is possible throughcombustion using the air 50 without the additional oxygen 52. Adjustmentof the heating rate also may include adjusting the throughput of theheat control supplies. For example, to increase the rate of heating inthe heat control mode 94, controller 22 may increase the flow rate ofHCF 54 and also adjust the flow rates of air 50 and oxygen 52 to controlto a desired oxygen content in oxygen enriched air 40 and/or a desiredlevel of excess air. In another embodiment, the heat control mode 94includes an air/fuel heat mode 102 in which the air already contains ahigher percentage of oxygen, and the heat control transition 100 maytransition the air/fuel heat mode 102 to an oxygen enriched air/fuelheat mode 104 in which the air contains an even higher percentage ofoxygen and lower percentage of nitrogen.

FIG. 3 is a schematic representation of an embodiment of certaincomponents of the gasification system 10 of FIG. 1 for use when thefirst injector 14 is designed for both heating of the gasifier 12 andgasification. That is, the first injector 14 may be a combinationinjector (e.g., combi-injector) configured to inject the HCF 54 and theoxygen enriched air 40 into the gasifier 12 for combustion during a heatcontrol mode and to inject the gasification fuel 24 and gasificationoxidant 56 into the gasifier 12 for gasification during a gasificationmode 116. The controller 22 may operate the injector 14, gasifier 12,and supply valves 80 according to controls for the preheat mode 96, asdescribed in relation to the heat control mode 94 of FIG. 2. The preheatmode 96 includes transitioning from the air/fuel heat mode 102 to theoxygen enriched air/fuel heat mode 104 prior to gasification. Aspreviously discussed, this transition may be accomplished by increasingthe additional amount of oxygen 52 added to air that is already enrichedwith oxygen in the air/fuel heat mode 102. In this way, the gasifier 12may be preheated using only oxygen enriched air. Once the thresholdtemperature of the refractory liner 36 is reached, the controller 22 mayreconfigure the injector 14 for use in the gasification mode 116 basedon sensor feedback. First, to transition to the gasification mode 116,the valves 80 corresponding to the heat control supplies 92 may beclosed in order to allow the gasification supplies 118 to flow throughthe same passages of the injector 14 and into the gasifier 12 forgasification. Second, the valves 80 corresponding to the gasificationfuel 24, gasification oxidant 56, nitrogen 58, and steam 60 may beopened to provide the gasification supplies 118 to the injector 14. Atsome time, it may be desirable to take the gasifier offline, e.g.,transitioning from the gasification mode 116 to the heat maintenancemode 98. Accordingly, the controller 22 may operate the valves 80 toblock the gasification supplies 118 and then enable the heat controlsupplies 92. Accordingly, the controller 22 may operate the valves 80,injector 14, and gasifier 12 according to the heat maintenance mode 98described previously, including transitioning from the air/fuel heatmode 102 to the oxygen enriched air/fuel heat mode 104. Thus, the sameinjector 14 may be operated in and transitioned between the preheat mode96, gasification mode 116, and heat maintenance mode 98. The process oftransitioning between these three operating modes includes many othersteps, which are described in detail below in relation to FIGS. 4-6.

It should be noted that the modes (e.g., preheat mode 96, heatmaintenance mode 98, gasification mode 116, air/fuel heat mode 102, andoxygen enriched air/fuel heat mode 104) in the controller 22 may includecode or instructions that are encoded in programs that may be executedto calculate appropriate positions of the valves 80. The code orinstructions may be stored in any suitable article of manufacture thatincludes at least one tangible non-transitory, machine readable medium,such as a memory of the controller 22, a computing device having thecontroller 22, etc.

FIGS. 1-3 illustrate a gasification system that enriches air withadditional oxygen to supply the oxygen enriched air 40 for heating thegasifier. In addition, a similar effect may be achieved by manufacturingan oxygen enriched air from its constituent parts (i.e., nitrogen andoxygen). A gasification system that operates by mixing air in this wayis described in detail below. The flow charts of FIGS. 4-6 areapplicable to both gasification systems that enrich air (e.g., addoxygen to air) supplied by an air supply, and systems that mix air fromnitrogen and oxygen.

FIG. 4 is a flow chart of an embodiment of a method 130 for heating agasifier with oxygen enriched air or a manufactured air using a preheatinjector, such as the injector of FIG. 2. This injector may be usedspecifically to preheat the gasifier to a desired temperature prior togasification using oxygen enriched air or manufactured air. Aspreviously mentioned, using air enriched with a higher content of oxygenand an appropriately adjusted (e.g., decreased) proportion of air forcombustion to heat the refractory liner of the gasifier may allow thegasifier to reach a higher temperature than would be possible using airwith a lower content of additional oxygen, while also providing a fasterrate of heating. Consequently, the gasifier may remain at an appropriategasification temperature for a longer amount of time. It should be notedthat at least some or all of the steps listed in the method 130 may becomputer implemented steps, and thus may correspond to code orinstructions stored on a non-transitory, tangible, machine readablemedium, such as a memory.

The method 130 includes installing the preheat injector onto thegasifier, as represented by block 132. Installation may include couplingand sealing the injector with an opening of the gasifier and connectingappropriate feeds of the heat control supplies (e.g., HCF, air, andadditional oxygen) to the injector. After installation, the method 130includes preheating the gasifier with an enriched/manufactured air heatcontrol mode (block 134). The enriched air heat control mode correspondsto an oxygen enriched air heat mode, where air is enriched withadditional oxygen, and the manufactured air heat mode corresponds to anenriched mixed air heat mode, where nitrogen and oxygen are mixed tocreate an oxygen enriched air. Specific steps for preheating thegasifier are discussed in detail below, including a transition from anair heat mode to an oxygen enriched air heat mode. The method 130further includes monitoring and controlling the enriched/manufacturedair heat control mode until the gasifier reaches the thresholdtemperature (block 136). The temperature threshold may be a preset valuebased on the particular gasifier in use and/or the specific gasificationprocess. Upon reaching the threshold temperature for the gasificationprocess, the enriched/manufactured air heat control mode may be shutdown (block 138). Shutting down the enriched/manufactured air heatcontrol mode, discussed in detail below, may include a reversal of thesteps taken to preheat the gasifier.

Once the enriched/manufactured air heat control mode is shut down, themethod 130 includes replacing the preheat injector with a gasificationinjector (block 140), i.e., an injector that may be operated in agasification mode. In other words, the preheat injector and thegasification injector are two separate injectors, which may be mutuallyexclusively mounted to an inlet of the gasifier. The gasificationinjector may be used to inject the gasification supplies (e.g., thegasification fuel, oxidant, and moderator) into the gasifier forgasification. During the time used to replace the injectors, e.g.,uncoupling the first (preheat) injector from the gasifier and couplingthe second (gasification) injector to the gasifier, the temperature ofthe refractory liner in the gasifier may begin to lose heat. Bypreheating the gasifier temperature to a relatively higher temperatureusing the oxygen enriched air, the gasifier may remain above thetemperature threshold long enough for installation of the gasificationinjector. This additional heat and time may substantially reduce thepossibility of the gasifier cooling below a lower temperature thresholdsuitable for gasification.

After replacing the preheat injector with the gasification injector, themethod includes purging the system of oxygen (block 142). Thegasification process may be performed under relatively fuel richconditions, while preheating is performed under relatively fuel leanconditions. Therefore, it may be desirable to purge the system ofresidual gases before transitioning from a heating mode to thegasification mode and vice versa. The method 130 then includes startingthe gasification supplies to initiate a gasification mode in thegasifier (block 144). This may include supplying the gasification fuel,gasification oxidant, and moderator, which may include one or both ofsteam and nitrogen, to the gasifier for converting the gasification fuelinto syngas. The method 130 also includes monitoring and controlling thegasification mode in the gasifier (block 146). This may be accomplishedby the controller 22, as shown in FIG. 3, where the controller isconfigured to operate the injector, gasifier, supply valves, and othercomponents during the gasification mode. The gasification process may becontrolled based on sensor feedback received by the controller fromsensors placed throughout the gasification system. The method 130further includes shutting down the gasification mode under certainconditions (block 148). One such condition may include a need formaintenance, service, or repair, which may be determined throughfeedback from sensors located in the gasifier, injector, gasificationfuel supply, gas treatment unit, and the like. When the gasificationmode is shut down, the method 130 includes purging/evacuating the syngasfrom the gasifier (block 150). This may be accomplished bydepressurizing the gasifier, establishing a vacuum between the gasifierand the injector, and injecting a purge supply of nitrogen and/or steaminto the gasifier through the injector as operated by the controller. Asa result, the produced syngas may be evacuated from the gasificationchamber to the gas treatment unit for treatment and eventual use indownstream processes, power generation, or chemical production.

After gasification, the method 130 includes replacing the gasificationinjector with a heat maintenance injector (block 152). This injector,like the preheat injector, may be utilized in the heat control mode, andin certain embodiments the injector may be the same as the preheatinjector. The heat maintenance injector is then used to maintain heat inthe gasifier with the enriched/manufactured air heat control mode (block154). The enriched/manufactured air heat control mode for heatmaintenance is described in detail below, and uses a similar sequence ofsteps as the enriched/manufactured air heat mode for preheating thegasifier. The difference is that the preheating process introduces heatto the gasifier prior to gasification, while the heat maintenance isused to maintain heat that is already present in the gasifier beforegasification. In the illustrated embodiment, the heat maintenance isused to maintain heat in the gasifier after gasification but beforestarting gasification again. In other embodiments, however, the heatmaintenance may be used to maintain heat in the gasifier afterpreheating the gasifier but before beginning gasification. As before,the controller may monitor and control the enriched/manufactured airheat control mode (block 156) in order to maintain a temperature of thegasifier above a threshold temperature. This threshold temperature maybe the same threshold temperature desired for preheating the gasifierwith the preheat injector. The method 130 then includes shutting downthe enriched/manufactured air heat control mode when the gasificationsystem is ready for the gasification mode (block 158), and replacing theheat maintenance injector with the gasification injector (block 160).This may begin the process again starting from block 142, as the systemis operated in gasification mode.

FIG. 5 is a flow chart of an embodiment of a method for heating agasifier with oxygen enriched/manufactured air and operating thegasifier using a combination injector (e.g., heat control injector andgasification injector). Many steps in the method 162 are similar tothose from method 130 of FIG. 4, and at least some or all of the stepsmay be computer implemented steps corresponding to code or instructionsstored on a non-transitory, tangible, machine readable medium, such as amemory. Since this method 162 uses a combination injector, the sameinjector may be operated in both the enriched/manufactured air heatcontrol mode and the gasification mode. In addition, the combinationinjector may be used for preheating the gasifier as well as maintainingheat in the gasifier when not operating in the gasification mode.Instead of replacing one injector for another when switching betweenmodes, the same injector is reconfigured from the enriched/manufacturedair heat mode to the gasification mode and vice versa.

The method 162 includes installing the combination injector onto thegasifier (block 164), configuring the combination injector for preheat(block 166), and preheating the gasifier with the enriched/manufacturedair heat control mode (block 168). The method 162 also includesmonitoring and controlling the enriched/manufactured air heat controlmode until the gasifier reaches a threshold temperature (block 170) andshutting down the enriched/manufactured air heat control mode uponreaching the threshold temperature and when ready for gasification mode(block 172). The combination injector may then be configured forgasification (block 174), instead of being replaced by a differentinjector. Further, the method 162 includes purging the system of oxygen(block 176), which may include flowing nitrogen or steam through thecombination injector, before starting a flow of the gasificationsupplies to initiate the gasification mode in the gasifier (block 178).The gasification mode may be monitored and controlled by the controller(block 180), and shut down under certain conditions (block 182) such asa need for maintenance, service, or repair.

The method 162 further includes purging/evacuating the gasificationsystem of syngas (block 184) before configuring the combination injectorfor heat maintenance (block 186). In the heat maintenance configuration,the combination injector maintains heat in the gasifier with theenriched/manufactured air heat control mode (block 188), and thecontroller monitors and controls the enriched/manufactured air heatcontrol mode to maintain the gasifier above the threshold temperature(block 190) before shutting down the enriched/manufactured air heatcontrol mode when the system is ready for the gasification mode (block192). Still further, the method includes configuring the combinationinjector for gasification (block 194), which starts the method 162 againbeginning with purging the oxygen (block 176). In this way, the gasifiermay be cycled through heating using air enriched (or manufactured) tohave higher oxygen content and gasification of the gasification fuel,all using the same combination injector.

FIG. 6 is a flow chart of an embodiment of a method 196 for operatingcertain components of a gasification system in an oxygen enriched airheat mode. This method 196 includes steps that apply for operating thegasification system in the oxygen enriched air heat mode for preheatingand/or maintaining heat in the gasifier, as described in FIGS. 4 and 5,using either a preheat injector or a combination injector. The method196 details the steps encompassed by preheat blocks 134, 136, and 138and heat maintenance blocks 154, 156, and 158 for the preheat injectorin FIG. 4, as well as preheat blocks 168, 170, and 172 and heatmaintenance blocks 188, 190, and 192 for the combination injector inFIG. 5. As mentioned previously, the method 196 includes one or moresteps that may be computer implemented steps that correspond to code orinstructions stored on a non-transitory, tangible, machine readablemedium, such as a memory.

The method 196 includes starting the enriched air heat control mode(block 198), beginning with establishing aspiration (block 200) betweenthe injector and the gasifier. This may be accomplished by using steamor a vacuum pump to establish aspiration through the gasifier from theinjector inlet through the gasifier outlet, and installing the injectorfor enriched air heat mode operation. Once the injector is installed,the method 196 includes purging the lines, injector, and gasifier of thegasification system (block 202). This purge may be accomplished byflowing an inert gas (e.g., nitrogen) from the purge supply through theinjector and the gasifier in order to rid these components of residualsubstances from earlier gasification or heating processes. The method196 also includes maintaining a trickle purge through certain lines andpassages of the injector (block 204). The trickle purge may be arelatively low flow of the inert gas through the injector passages inorder to inhibit accumulation of substances within injector passagesthat are not being used. Trickle purges may be adjusted as other flowsare introduced into the injector. For example, the method 196 includesstarting a pilot or initial air flow to the injector (block 206) andsubsequently or simultaneously starting a fuel flow to the injector(block 208). As each flow is started, the trickle purge of inert gasflowing through specific passages of the injector may be decreased untilthe full pilot or initial air flow or fuel flow is established in thepassages. In other embodiments, the trickle flow may be curtailed at thesame time as or just prior to introducing the respective pilot orinitial flow to a passage. The air/fuel mixture is then ignited by anigniter to establish combustion for the air/fuel heat mode of heatcontrol (e.g., preheat or heat maintenance) in the gasifier (block 210).This combustion may begin to heat the refractory liner toward thedesired threshold temperature.

In order to further increase the temperature and the rate of temperatureincrease of the refractory liner toward the threshold temperature, themethod 196 includes enriching the air with oxygen to transition from theair/fuel heat mode to the enriched air/fuel heat mode of heat control inthe gasifier (block 212). That is, additional oxygen may beprogressively introduced into the airflow through the injector to enrichthe air with oxygen while decreasing the air flow, thereby increasingthe temperature produced through combustion of the HCF and oxygenenriched air. It may be desired for the throughput of the injector to beadjusted or the gasifier to be pressurized (block 214) as part of theheat mode operation. Throughput adjustments, as well as adjustments inthe degree of oxygen enrichment and of excess air, may be made inresponse to the heating requirements for the refractory. Duringpreheating and heat maintenance with a dedicated preheat or heatmaintenance injector, the pressure of the gasifier is typically heldunder a slight vacuum, at atmospheric pressure, or slightly higher thanatmospheric pressure. However, when operating with a combinationinjector (combi-injector), the gasifier may be pressurized to maintainone or more injector velocities below a velocity that would otherwiseextinguish or destabilize the flame in the gasifier. The gasifier may bepressurized to a gasification pressure within a range of approximately20 to 2500, 50 to 2000, 100 to 1500, or 350-1200 psi. For example, thegasifier pressure may be elevated to a pressure above approximately30-40 psi and below approximately 2500 psi.

The method 196 further includes monitoring the gasifier temperature(block 216) by measuring the temperature of the gasifier with a sensorthat communicates the recorded temperature to the controller. Thecontroller may control the enriched air/fuel heat mode until thegasifier reaches the desired heat control temperature threshold (block218) for the gasification system operating in the heat control mode. Atthis point, the method 196 includes initiating a shutdown of the heatcontrol of the gasifier (block 220), which may be accomplished throughthe following three steps of the method 196. First, the oxygen flow isshut down and purged (block 222), then the fuel flow is shut down andpurged (block 224), and finally the air flow is shut down and purged(block 226). In effect, this may correspond to transitioning thegasification system from the oxygen enriched air heat control mode tothe air heat control mode before shutting down the flow of heat controlfuel and air in the system. The various purges may be accomplished byflowing increased amounts of inert gas into the injector passages as theflows are each shut down. It should be noted that the flows are shutdown (blocks 222, 224, and 226) in the opposite order in which they werepreviously introduced (blocks 206, 208, and 212) to the injector. Onceall flows are shut down, the gasification system is purged (e.g., thelines, injector, and gasifier) with the purge supply of inert gas (block228), readying the gasifier for the flow of the gasification supplies.In addition, the gasifier may be depressurized as the flows are beingshut down (blocks 222, 224, 226) or as the gasification system is beingpurged (block 228).

FIG. 7 is a plot 240 modeling embodiments of available gasifier heatingwhen operating a gasification system in different heat modes. The plot240 illustrates a flame temperature of the gasifier (ordinate 242)against a percentage of excess oxygen injected into the gasifier(abscissa 244). The three curves 246, 248, and 250 depicted across theplot 240 represent the variation of an adiabatic flame temperature withrespect to the percentage of excess oxygen. The first curve 246corresponds to an adiabatic flame temperature calculated for a flameproduced by igniting heat control fuel (e.g., HCF 54) with 100% air,without any additional oxygen. The second curve 248 corresponds to anadiabatic flame temperature produced by the combustion of heat controlfuel (e.g., HCF 54) using a mixture of 90% air and 10% additionaloxygen, by volume. Finally, the third curve 250 corresponds to anadiabatic flame temperature produced by the combustion of heat controlfuel (e.g., HCF 54) using 80% air and 20% additional oxygen, by volume.The plot 240 shows that as a greater amount of oxygen is added to theair/fuel mixture injected into the gasifier 12 for heating the gasifier12, the temperature of the gasifier 12 is increased for a givenpercentage of excess oxygen.

In addition to the three curves 246, 248, and 250, the plot 240 includestwo operating windows 252 and 254. These operating windows 252 and 254reflect the effective operating temperature of the refractory liner 36for the curves 246 and 248, respectively. For example, an upper lefthand corner of window 252 may represent a maximum temperature that maybe achieved by heating the gasifier based on a minimum excess oxygenpercentage limit 256. This minimum excess oxygen percentage limit 256may be, for example, approximately fifteen percent excess oxygen for theair/fuel heat mode (with no additional oxygen). Similarly, looking atwindow 254, a minimum excess oxygen percentage limit 258 exists for airenriched with 10% additional oxygen, and this minimum limit 258 islarger than the excess oxygen percentage limit 256. In the illustratedembodiment, a distance 260 between the operating window 252 and thecorresponding adiabatic curve 246 taken at the minimum excess oxygenpercentage limit 256 is approximately equal to a distance 262 betweenthe operating window 254 and the corresponding adiabatic curve 248 takenat the minimum excess oxygen percentage limit 258. A lower right handcorner of each of the operating windows 252 and 254 may represent amaximum excess oxygen percentage limit related to a minimum gasifiertemperature 264. That is, in order to reach the desired gasifiertemperature 264 during the final stages of heating, there is a maximumpercentage of excess oxygen that may be used with the heat control fuel(e.g., HCF 54) used to heat the gasifier for a given air/oxygen mixtureratio. A distance 266 between the lower right hand corner of theoperating window 252 and the corresponding adiabatic curve 246 isapproximately equal to a distance 268 between the lower right handcorner of the operating window 254 and the corresponding adiabatic curve248. The plot 240 shows that higher flame temperatures may be reached ata given percentage of excess oxygen by using air enriched withadditional oxygen for heating a gasifier, as compared to air without anyadditional oxygen. In addition, the higher flame temperature may beachieved while using a lower percentage of fuel, making the heatingprocess more fuel efficient. Still further, the higher flame temperaturealso may improve heat transfer for increasing a rate of heating towardthe final stages of preheating the gasifier. As the percentage of excessoxygen 244 is increased by injecting a higher composition of oxygen intothe gasifier, the controller may transition the gasification system fromthe air/fuel heat mode to the enriched air/fuel heat mode as the minimumlimit 258 of excess oxygen percentage is reached. This may berepresented by a transition from the first operating window 252 to thesecond operating window 254, allowing higher gasifier temperatures to bereached.

FIG. 8 is an axial perspective view of an embodiment of a combinationinjector 278 transitioning from the gasification mode 116 to an oxygenenriched/mixed air heat mode 280. The illustrated combination injector278 includes four passages 282, 284, 286, and 288 through which varioussupplies may be injected into the gasifier 12. The illustratedembodiment shows the passage 282 as a circular passage surrounded by theannular passages 284, 286, and 288 in a concentric or coaxialarrangement. These passages 282, 284, 286, and 288 may be defined bysubstantially circular walls 290, 292, 294, and 296, respectively, andeach wall may be axially fixed or movable relative to each other wall.In embodiments with movable walls, the controller 22 may change therelative position of the walls 290, 292, 294, and 296 (and thus angledtips 297) in order to control the relative flow rates and pressures ofthe gasification supplies 118 or heat control supplies 92 flowingtherethrough. In the gasification mode 116, the gasification supplies118 are configured to flow through the various passages 282, 284, 286,and 288 of the injector 278. For example, the nitrogen 58 may flowthrough the passage 288 while the gasification fuel 24 flows through thepassage 284 and the gasification oxidant 56 (e.g., oxygen) flows throughthe passages 282 and 286. The nitrogen 58 may be used to purge thegasification system as appropriate, and the gasification fuel 24 andoxidant 56 may be reacted in the gasifier 12 for producing syngas. Asthe nitrogen 58 is used to purge the system, one or more of the walls290, 292, 294, and 296 may be adjusted relative to each other to permituse of a relatively low flow rate of the nitrogen 58 through the passage288.

When the illustrated injector 278 is transitioned from the gasificationmode 116 to the oxygen enriched/mixed air heat control mode 280, theoxygen enriched air 40 (or mixed air using flows of nitrogen and oxygen)may be injected into the gasifier 12 through the passages 282, 286, and288 while the HCF 54 is injected through the passage 284. In someembodiments, the heat control mode 94 may control injection of nitrogeninto the gasifier 12 through the injection passage 284 along with theHCF 54. That is, the injector 278 may be configured to inject the heatcontrol fuel 54 and nitrogen through the fuel injection passage 284 andinject the air enriched with oxygen through at least one additionalinjection passage. The amount of the air in the at least one additionalinjection passage may be reduced to account for an increase in thenitrogen in the fuel injection passage 284, and this reduction of airmay be controlled by the heat control mode 94. The injection of theserelative amounts of the fuel 54, nitrogen, and enriched air 40 may beadjusted by the controller 22. An igniter 298 may be extended throughthe innermost passage 282 of the injector 278 to ignite the heat controlsupplies 92 entering the gasifier 12 for heating the gasifier 12.

When used to inject mixed air (e.g., using separate flows of nitrogenand oxygen) into the gasifier 12 for heating, the injector 278 may flowdifferent mixed air portions into the gasifier 12 through different fuelinjection passages 282, 284, 286, and 288. For example, the injectionpassage 284 may be configured to flow a first portion of the mixed airwith the heat control fuel 54 into the gasifier 12, where this portionof the mixed air is a portion of the nitrogen 326 without oxygen. Thismay create a diluted heat control fuel (DHCF) flow through the injectionpassage 284. At least one of the additional injection passages 282, 286,and 288 may inject portions of the mixed air, such as the oxygen 324, asecond portion of the nitrogen 326, air, or a combination thereof, intothe gasifier 12 as controlled by the heat control mode 94. Thecontroller 22 also may reduce the amount of air in the additionalpassages 282, 286, and 288 to account for an increase in the nitrogen inthe injection passage 284. The injector 278 may be configured to outputthe combined quantities of the oxygen 324, nitrogen 326, and/or airflowing through the injection passages 282, 284, 286, and 288 in adesired oxygen/nitrogen ratio. For example, the desired oxygen/nitrogenratio may be substantially equivalent to an oxygen/nitrogen ratio ofair, or the desired oxygen/nitrogen ratio may be richer in oxygen thanthe oxygen/nitrogen ratio of air. This allows the injector 278 to mixthe first mixed air portion and the second mixed air portion to createthe mixed air with an additional amount of the oxygen, creating anoxygen enriched mixed air for heating the gasifier 12. Flowing a portionof the nitrogen through the injection passage 284 with the fuel 54 mayrebalance the flows through the different passages, allowing theinjector 278 to operate in both the heat control mode and gasificationmode since the desired relative volumetric flow rates of mixed air andfuel flowing through the injector 278 may be different in the heatcontrol mode and the gasification mode. In other embodiments, at leastone fuel passage (e.g., the injector passage 284) of the injector 278may inject the heat control fuel 54 and a first portion of nitrogen intothe gasifier while at least one other passage may inject a secondportion of the nitrogen, oxygen, and/or air into the gasifier. Thecombined composition of the nitrogen, oxygen, and/or air may becontrolled to generate a mixed air with amounts of oxygen and nitrogensubstantially equivalent to air or substantially equivalent to an oxygenenriched air.

It should be noted that other arrangements of a combination injector maybe used to transition between operating in the gasification mode 116 andthe oxygen enriched air heat control mode 104. As an example, FIG. 9 isan axial perspective view of another embodiment of a combinationinjector 300 transitioning from the gasification mode 116 to an oxygenenriched air heat mode 280. This combination injector 300 includes fourpassages 302, 304, 306, and 308 defined by various walls that may befixed or movable relative to each other. Instead of establishing a purgeflow through one of the passages, the passage 302 may be sealed duringthe gasification mode 116 using a cooled insert 310. Flows of thegasification fuel 24 through passages 304 and 308 and a flow of thegasification oxidant 56 through passage 306 may be established to allowgasification of the gasification fuel 24 within the gasifier 12. As theinjector 300 is transitioned from the gasification mode 116 to theoxygen enriched air heat mode 280, the cooled insert 310 may be removedor sufficiently retracted from the innermost passage 302, allowing anadditional flow of the enriched air 40 to be introduced to the gasifier12 through the injector 300. In the enriched air heat mode 280, the HCF54 may flow through the passage 306 and the remaining amounts of theenriched air 40 may flow through the passages 304 and 308 into thegasifier 12, where combustion occurs. In addition, the igniter 298 maybe placed in or extended into the passage 302 for igniting the fuel/airmixture in the gasifier 12.

FIG. 10 is a schematic representation of an embodiment of a gasificationsystem 320 that may manufacture air for controlling the temperature ofthe gasifier 12. It should be noted that FIG. 10 includes similarelements as FIG. 1, and like elements are represented by like numbers inthe two figures. The elements of FIG. 10 with numbers corresponding tolike elements of FIG. 1 perform similar functions in both gasificationsystems 10 and 320, and will therefore not be reintroduced.

As previously mentioned, the gasification system 320 may create a mixedair (MA) 322 from independent supplies of oxygen 324 and nitrogen 326for heating of the gasifier 12. In addition to the MA supply 322, thesupply unit 20 may include a diluted heat control fuel (DHCF) supply 328that is a mixture of HCF 330 and nitrogen 332. The different supplies inthe supply unit 20, such as the DHCF supply 328 and mixed air supply322, may be injected into the gasifier 12 by a gasifier injector 334,similar to the injector 14 of FIG. 2. Generation of the mixed air 322from the oxygen 324 and the nitrogen 326 as well as the generation ofthe DHCF 328 may be controlled by the controller 22. The controller 22may also control the generation of the mixed air 322 with a ratio of theoxygen 324 to the nitrogen 326 that is substantially equivalent to air,or with a ratio to create an oxygen enriched mixed air. The gasificationfuel supply 26, oxidant supply 44, moderator supply 46, and purge supply48 may be arranged as previously described in FIG. 1.

FIG. 11 is a schematic representation of an embodiment of certaincomponents of the gasification system 320 of FIG. 10 including thegasifier injector 334 configured to heat the refractory liner 36 of thegasifier 12. Similar to the injector 14 of FIG. 2, the gasifier injector334 is configured to inject the heat control supplies 92 into thegasifier 12 for combustion during the heat control mode 94. In FIG. 11,however, these heat control supplies 92 include the DHCF 328 and themixed air 322, and the heat control supplies 92 may be generated andconveyed to the injector 334 in different ways, depending on thespecific control mode and injector configuration. For example, thegasification system 320 may be configured to create the mixed air 322with a ratio of the oxygen 324 and the nitrogen 326 that issubstantially equivalent to air, such as when operating in a mixedair/fuel heat mode 336. For further example, the gasifier injector 334may be configured to inject the heat control fuel 330 and the mixed air322 with an additional amount of the oxygen 324 into the gasifier 12 forcombustion during the heat control mode 94, so that the additionaloxygen 324 and the mixed air 322 combine to form an oxygen enrichedmixed air. The illustrated heat control mode 94 may include a heatcontrol transition 338 from the mixed air/fuel heat mode 336 to theoxygen enriched mixed air/fuel heat mode 340. That is, the gasifierinjector 334 may be configured to inject the mixed air 322 without theadditional amount of oxygen 324 during the mixed air/fuel heat mode 336and to inject the mixed air 322 with the additional amount of oxygen 324during the oxygen enriched mixed air/fuel heat mode 340. The controller22 may control amounts of the oxygen 324 and the nitrogen 326 forcreating both the mixed air 322 and the oxygen enriched mixed air basedon sensor feedback. In certain embodiments, the mixed air may becombined and vented to allow adjustment of the mixed air composition bycontroller 22 prior to introducing the mixed air through injector 334 toheat the gasifier 12.

FIG. 12 is a schematic representation of an embodiment of certaincomponents of the gasification system 320 of FIG. 10 where the gasifierinjector 334 is a combination injector. As previously described inrelation to FIGS. 3 and 11, the illustrated gasifier injector 334,gasification supplies 118, and heat control supplies 92 may becontrolled by the controller 22 to transition between the preheat mode96, gasification mode 116, and heat maintenance mode 98 based on sensorfeedback. The heat control supplies 92, including the independentsupplies of the oxygen 324 and the nitrogen 326 for creating the mixedair 322, may be controlled by the controller 22 as described in FIG. 11to transition between the mixed air/fuel heat mode 336 and the oxygenenriched mixed air/fuel heat mode 340 while preheating or maintainingheat within the gasifier 36.

FIGS. 11 and 12 illustrate the mixed air 322 being created upstream ofthe gasifier injector 334. This may be accomplished through a mixingdevice (e.g., mixing chamber) located upstream of the gasifier injector334 and designed to receive the oxygen 324 and the nitrogen 326 from theindependent supplies. The mixing device may then create and output themixed air 322 to the gasifier injector 334, as shown in the illustratedembodiment. In other embodiments, however, the gasifier injector 334 maybe configured to mix the oxygen 324 and the nitrogen 326, which flowdirectly into the gasifier injector 334 before being combined.

FIG. 13 is a flow chart of an embodiment of a method 350 for operatingcertain components of a gasification system in the heat control mode 94of FIG. 11 using the manufactured air 322 enriched with oxygen 324. Thismethod 350 includes steps that apply for operating the gasificationsystem of FIGS. 10-12 in the oxygen enriched air heat mode forpreheating or maintaining heat in the gasifier, as described in FIGS. 4and 5, using either a preheat injector or combination injector. Themethod 196 details the steps encompassed by preheat blocks 134, 136, and138 and heat maintenance blocks 154, 156, and 158 for the preheatinjector of FIG. 4, as well as preheat blocks 168, 170, and 172 and heatmaintenance blocks 188, 190, and 192 for the combination injector ofFIG. 5. As before, the method 350 includes one or more steps that may becomputer implemented steps that correspond to code or instructionsstored on a non-transitory, tangible, machine readable medium, such as amemory.

The method 350 includes several steps represented by equivalent blocks198, 200, 202, 204, 208, 214, 216, 220, 222, 224, and 228 in FIG. 6.Other steps in the method 350 are different, however, due to the processof manufacturing the mixed air in the gasification system. For example,the method 350 includes starting the enriched air heat control mode(block 198), establishing aspiration (block 200), purging thegasification system, e.g., lines, injector, and gasifier (block 202),and maintaining trickle purges in open injector passages (204). Afterthis, the method 350 includes executing the heat control mode bystarting a pilot or initial nitrogen flow (block 352), which is anitrogen flow of the nitrogen. The method 350 continues with starting apilot or initial oxygen flow (block 354), which is an oxygen flow of theoxygen, followed by generating the mixed air by mixing the nitrogen flowand the oxygen flow (block 356). Instead of introducing a flow of airfrom a separate compressor, these steps allow the air to be mixed to adesired ratio of oxygen to nitrogen (e.g., substantially equivalent toair) according to the heating mode. The method 350 further includesstarting a pilot or initial mixed air flow of the mixed air into thegasifier (block 358) before starting a pilot or initial fuel flow of theheat control fuel through the gasifier injector into the gasifier (block208). The method 350 then includes igniting the mixed air/fuel mixtureto establish combustion for the mixed air/fuel heat mode of heat controlin the gasifier (block 360). The mixed air may then be enriched withoxygen to transition the combustion from the mixed air/fuel heat mode tothe oxygen enriched mixed air/fuel heat mode (block 362). Afterpressurizing the gasifier and/or adjusting the throughput of the flows(block 214) and while monitoring the gasifier temperature (block 216),the method 350 includes controlling the enriched mixed air/fuel heatmode until the gasifier reaches the desired heat control temperature(block 364). Shutting down the heat control of the gasifier follows thesame steps as outlined in FIG. 6 (blocks 220, 222, and 224), but afterthe oxygen and fuel flows are shut down, the only remaining flow intothe gasifier is the nitrogen because the mixed air of the air/fuelmixture is manufactured from the oxygen and nitrogen flows. Therefore,the method 350 concludes with shutting down and purging the nitrogenflow (block 366) and purging the gasification system (block 228).

FIG. 14 is a schematic representation of an embodiment of certaincomponents of a gasification system with a heat control injector (e.g.,preheat or heat maintenance injector), including flow lines formanufacturing (e.g., from independent flows of oxygen and nitrogen) airand/or enriching air with oxygen. As previously shown in FIGS. 2 and 11,the gasification system 10, 320 includes a preheat injector 14, 334 usedto inject a heat control fuel and either air, oxygen enriched air ormixed air into the gasifier 12 for combustion during the heat controlmode. The heat control fuel may be the heat control fuel 54 or thediluted heat control fuel 328. The illustrated embodiment includes flowlines 400 used when the system 10, 320 operates in the oxygen enrichedair/fuel heat mode 104, and flow lines 402 used when the system 10, 320operates in the oxygen enriched mixed air/fuel heat mode 340. In eithermode, the system 10, 320 establishes pilot flows of air or mixed air andfuel to the injector 14, 334 via pilot flow lines 404 for combustion,producing a flame 406 to heat the gasifier 12. Main flow lines 408 areused to convey additional heat control fuel 54, 328 and oxygen enrichedair to the heat control injector 14, 334 to further increase thetemperature of the gasifier 12.

The controller 22 may communicate with flow/pressure control devices 410located along different flow lines 400, 402, 404, and 408 in order tocontrol the flow rate and pressure of the different supplies enteringthe injector 14, 334. These devices 410 may include valves, such as thevalves 80 of FIGS. 1-3 and 10-12. The controller 22 may control thedevices 410 to either supply the air 50, or to mix the nitrogen 326 andthe oxygen 52, 324 for producing mixed air, to the pilot and main flowlines 404 and 408. In addition, the controller 22 may receive feedbackfrom a mixed air composition check device 412 when operating in theenriched mixed air/fuel heat mode 340. This device 412 may monitor thecomposition of the mixed air flowing therethrough (e.g., relativeamounts of the oxygen 324 and the nitrogen 326 combined from flow lines402), and the controller 22 may adjust the flows of these suppliesaccordingly to achieve the desired mixture of nitrogen and oxygen toproduce mixed air (e.g., substantially equivalent to air). A similaroxygen enriched air composition check device 414 may be located alongthe main flow line 408 to monitor the composition of the air (e.g., air50 or mixed air from flows of nitrogen 326 and oxygen 52, 324) afterenrichment with the additional oxygen 52. The controller 22 may controlan ignition system 416 based on the concentrations of the air and fuelmixture within the injector 14, 334 and receive feedback regardingcombustion from a flame detection system 418. Finally, the controller 22is configured to receive gasifier temperature feedback from thetemperature sensor 64 within the gasifier 12. Other arrangements of thesupplies, flow lines, and control devices may be employed in thegasification system 10, 320 in order to supply a desired mixture of air(manufactured and/or enriched with oxygen) to the injector 14, 334.

FIG. 15 is a schematic representation of an embodiment of certaincomponents of a gasification system with a combination injector,including flow lines for manufacturing air and/or enriching air withoxygen. The illustrated injector may perform the functions of injectors14 and 334 as shown in FIGS. 3 and 12, respectively. That is, theinjector 14, 334 is configured to transition between operation in aheating mode (e.g., preheat mode 96 or heat maintenance mode 98) and ina gasification mode 116. The system includes flow lines for conveyingthe various heat control supplies and gasification supplies toappropriate passages within the injector 14, 334 through inlet ports ornozzles 430. Each of the nozzles 430 may introduce different suppliesinto different passages within the injector 14, 334, such as thepassages detailed in FIGS. 8 and 9. The supplies may include the air 50,additional oxygen 52, 324, nitrogen 326, HCF 54, 330, nitrogen 332 fordiluting the HCF 54, 330, gasification fuel 24, and gasification oxidant56. The gasification oxidant 56 may be oxygen provided from the samesupply as the additional oxygen 52, 324 for the heat control mode or mayflow to the injector 14, 334 from a separate supply through a differentflow line.

The illustrated embodiment includes flow lines 432 that may be used whenthe air is supplied and other flow lines 434 that may be used when theair is mixed from independent supplies of the nitrogen 326 and oxygen324. Certain flow lines 436 may be optional flow lines that may beopened and used to rebalance the flow of different supplies through theinjector 14, 334 or provide additional flow paths for the correspondingsupplies. Flow/pressure control devices 438 placed throughout the flowlines may control the flow rate and pressure of the supplies into theinjector 14, 334, and composition check devices 440 may determine thecomposition of fuel or incoming air. The composition may be provided tothe controller 22 as feedback for controlling the flow/pressure controldevices 438. Flow control devices 442 also may be positioned upstream ofeach of the nozzles 430 to control the flow of different supplies intothe injector 14, 334 according to the mode of operation of thegasification system.

Technical effects of the invention include, among other things, allowinga refractory liner of a gasifier to be heated above a thresholdtemperature using oxygen enriched air. Because of the relativelydecreased concentration of nitrogen and increased concentration ofoxygen with the air used for combustion to heat the gasifier, thegasifier may reach a higher temperature than would be possible using airwithout a higher content of oxygen for heating the gasifier. Thecontroller may transition the gasification system between an air/fuelheat mode and an oxygen enriched air/fuel heat mode by simultaneouslyreducing the flow rate of air while enriching the air with oxygen as itflows into the gasifier through the injector. By heating the gasifier toa higher temperature, the system allows the gasifier to maintain anappropriate temperature for gasification for a relatively longer amountof time. In addition, the higher concentration of oxygen present in theair used to preheat the gasifier may increase the rate of the gasifierpreheat and efficacy of fuel use, thereby heating the gasifier to anappropriate gasification temperature faster while using less fuel.Manufacturing the air used for heating the gasifier from independentsupplies of nitrogen and oxygen may provide greater flexibility incontrolling the relative concentrations of nitrogen and oxygen of themixed air. In addition, by mixing the nitrogen and oxygen to produce themixed air, the gasification system may operate without a separate aircompressor, utilize flow lines and gas supplies that already exist intypical gasification systems, and redistribute flows of fuel and mixedair within the injector to balance the rates at which these suppliesflow into the gasifier.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

1. A system, comprising: a gasifier injector configured to inject a heatcontrol fuel and a mixed air into a gasifier for combustion during aheat control mode, wherein the heat control fuel is the same ordifferent from the gasification fuel, and the system is configured tocreate the mixed air from independent supplies of oxygen and nitrogen.2. The system of claim 1, comprising a mixing device upstream from thegasifier injector, wherein the mixing device is configured to receivethe oxygen and the nitrogen from the independent supplies, and themixing device is configured to create and output the mixed air to thegasifier injector.
 3. The system of claim 1, wherein the gasifierinjector is configured to mix the oxygen and the nitrogen to create andoutput the mixed air to the gasifier.
 4. The system of claim 3, whereinthe gasifier injector comprises a first injection passage configured toflow a first mixed air portion, and a second injection passage to flow asecond mixed air portion.
 5. The system of claim 4, wherein the firstinjection passage is configured to flow the first mixed air portion andthe heat control fuel, and the first mixed air portion comprises a firstportion of the nitrogen without the oxygen.
 6. The system of claim 5,wherein the second mixed air portion comprises a second portion of thenitrogen with the oxygen.
 7. The system of claim 6, wherein the gasifierinjector is configured to mix the first mixed air portion and the secondmixed air portion to create the mixed air with a ratio of the oxygen andthe nitrogen that is substantially equivalent to air.
 8. The system ofclaim 6, wherein the gasifier injector is configured to mix the firstmixed air portion and the second mixed air portion to create the mixedair with an additional amount of the oxygen, and the mixed air with theadditional amount of the oxygen creates an oxygen enriched mixed air. 9.The system of claim 1, wherein the system is configured to create themixed air with a ratio of the oxygen and the nitrogen that issubstantially equivalent to air.
 10. The system of claim 1, wherein thegasifier injector is configured to inject the heat control fuel and themixed air with an additional amount of the oxygen into the gasifier forcombustion during the heat control mode, and the mixed air with theadditional amount of the oxygen creates an oxygen enriched mixed air.11. The system of claim 10, wherein the heat control mode comprises aheat control transition from a mixed air/fuel heat mode to an oxygenenriched mixed air/fuel heat mode, the gasifier injector is configuredto inject the mixed air without the additional amount of the oxygenduring the mixed air/fuel heat mode, and the gasifier injector isconfigured to inject the mixed air with the additional amount of theoxygen during the oxygen enriched mixed air/fuel heat mode.
 12. Thesystem of claim 10, comprising a controller configured to controlamounts of the oxygen and the nitrogen to create both the mixed air andthe oxygen enriched mixed air based on sensor feedback.
 13. The systemof claim 1, comprising the gasifier having a gasification chamber, arefractory liner disposed about the gasification chamber, and anenclosure disposed about the refractory liner, wherein the heat controlmode is configured to control heating of the refractory liner to atemperature at or above a temperature threshold while the gasifier isnot operating in the gasification mode.
 14. The system of claim 1,wherein the gasifier injector is configured to inject a first mixture ofthe heat control fuel and a first portion of the nitrogen via a fuelpassage, and the gasifier injector is configured to inject the oxygen,or a second portion of the nitrogen, or air, or a combination thereof,through at least one additional injection passage.
 15. The system ofclaim 14, wherein an amount of the air in the at least one additionalinjection passage is reduced to account for an increase in the nitrogenin the fuel injection passage.
 16. The system of claim 14, wherein thegasifier injector is configured to output quantities of the oxygen, thenitrogen, and/or the air in a first oxygen/nitrogen ratio, wherein thefirst oxygen/nitrogen ratio is either substantially equivalent to asecond oxygen/nitrogen ratio of air, or the first oxygen/nitrogen ratiois richer in oxygen than the second oxygen/nitrogen ratio of air.
 17. Asystem, comprising: a controller configured to control a heat controlmode of a gasifier injector coupled to a gasifier, wherein the heatcontrol mode of the gasifier injector is configured to control injectionof a heat control fuel and a mixed air into the gasifier for combustion,the heat control fuel is the same or different from a gasification fuelused during a gasification mode in the gasifier, the controller isconfigured to control generation of the mixed air from independentsupplies of oxygen and nitrogen, and the heat control mode is configuredto control heating of the gasifier to a temperature at or above atemperature threshold while the gasifier is not operating in thegasification mode.
 18. The system of claim 17, wherein the controller isconfigured to control the generation of the mixed air with a ratio ofthe oxygen and the nitrogen that is substantially equivalent to air. 19.The system of claim 17, wherein the controller is configured to controla ratio of the oxygen and the nitrogen to generate the mixed air with anadditional amount of the oxygen, and the mixed air with the additionalamount of the oxygen creates an oxygen enriched mixed air.
 20. Thesystem of claim 19, wherein the heat control mode comprises a heatcontrol transition from a mixed air/fuel heat mode to an oxygen enrichedmixed air/fuel heat mode, the gasifier injector is configured to injectthe mixed air without the additional amount of the oxygen during themixed air/fuel heat mode, and the gasifier injector is configured toinject the mixed air with the additional amount of the oxygen during theoxygen enriched mixed air/fuel heat mode.
 21. The system of claim 17,wherein the controller is configured to execute the heat control modeby: starting a nitrogen flow of the nitrogen; starting an oxygen flow ofthe oxygen; generating the mixed air with the nitrogen flow and theoxygen flow; starting a mixed air flow of the mixed air into thegasifier; starting a fuel flow of the heat control fuel through thegasifier injector into the gasifier; igniting a mixture of the mixed airflow and the fuel flow to establish combustion for a mixed air/fuel heatmode.
 22. The system of claim 21, wherein the controller is configuredto execute the heat control mode by: enriching the mixed air with anadditional amount of the oxygen to transition the combustion from themixed air/fuel heat mode to an oxygen enriched mixed air/fuel heat mode.23. The system of claim 17, wherein the heat control mode is configuredto control injection of a first mixture of the heat control fuel and afirst portion of the nitrogen through a fuel injection passage of thegasifier injector, and the heat control mode is configured to controlinjection of the oxygen, or a second portion of the nitrogen, or air, ora combination thereof, through at least one additional injection passageof the gasifier injector.
 24. The system of claim 23, wherein thecontroller is configured to reduce an amount of the air in the at leastone additional injection passage to account for an increase in thenitrogen in the fuel injection passage.
 25. A method, comprising:controlling a heat control mode of a gasifier injector coupled to agasifier, wherein controlling the heat control mode comprises:controlling generation of a mixed air from independent supplies ofoxygen and nitrogen; and controlling injection of a heat control fueland the mixed air into the gasifier for combustion, wherein the heatcontrol fuel is the same or different from a gasification fuel usedduring a gasification mode in the gasifier; and controlling heating ofthe gasifier to a temperature at or above a temperature threshold whilethe gasifier is not operating in the gasification mode.
 26. The methodof claim 25, wherein controlling the heat control mode comprises:starting a nitrogen flow of the nitrogen; starting an oxygen flow of theoxygen; generating the mixed air with the nitrogen flow and the oxygenflow; starting a mixed air flow of the mixed air into the gasifier;starting a fuel flow of the heat control fuel through the gasifierinjector into the gasifier; igniting a mixture of the mixed air flow andthe fuel flow to establish combustion for a mixed air/fuel heat mode.27. The method of claim 25, comprising: controlling injection of a firstmixture of the heat control fuel and a first portion of the nitrogenthrough a fuel injection passage of the gasifier injector; andcontrolling injection of the oxygen, or a second portion of thenitrogen, or air, or a combination thereof, through at least oneadditional injection passage of the gasifier injector.